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	| class Delegator: | |
| def __init__(self, delegate=None): | |
| self.delegate = delegate | |
| self.__cache = set() | |
| # Cache is used to only remove added attributes | |
| # when changing the delegate. | |
| def __getattr__(self, name): | |
| attr = getattr(self.delegate, name) # May raise AttributeError | |
| setattr(self, name, attr) | |
| self.__cache.add(name) | |
| return attr | |
| def resetcache(self): | |
| "Removes added attributes while leaving original attributes." | |
| # Function is really about resetting delegator dict | |
| # to original state. Cache is just a means | |
| for key in self.__cache: | |
| try: | |
| delattr(self, key) | |
| except AttributeError: | |
| pass | |
| self.__cache.clear() | |
| def setdelegate(self, delegate): | |
| "Reset attributes and change delegate." | |
| self.resetcache() | |
| self.delegate = delegate | |
| if __name__ == '__main__': | |
| from unittest import main | |
| main('idlelib.idle_test.test_delegator', verbosity=2) | |